That really sucks. I hope it was just a joy ride and not a chop shop and he gets it back in one piece. The person I sold my coupe to last month had his previous 66 coupe stollen in Oakland and only got back a shell.
I really don't know the story behind it getting stolen. He's in same local Mustang club as I'm in, the club President had sent out an e-mail.
Kill switchs or anything that slows them down is always a good idea. I have a hidden MSD kill switch. The motor will turn over but the plugs will not fire. I figure with this at least they will have to bring a tow truck.